@mixin border-1px($color){
  position: relative;
  &::after{
    display: block;
    position: absolute;
    left: 0;
    bottom: 0;
    width: 100%;
    border-top: 1px solid $color;
    content: '';
  }
}
@mixin bg-image($url){
  background-image: url($url+"@2x.png");
  @media (-webkit-min-device-pixel-ratio:3),
  (min-device-picel-ratio:1.5){
    background-image: url($url+"@3x.png");
  }
}